Curved Toroidal Row Column Addressed Transducer for 3D Ultrafast Ultrasound Imaging

Area of Science:

• Medical Imaging
• Ultrasound Technology
• Cardiovascular Research

Background:

• High-frame-rate 3D ultrasound imaging is crucial for cardiac applications but hindered by electronic complexity and cost.
• Existing Row Column Addressed (RCA) transducers offer low channel count for ultrafast 3D imaging but have field-of-view limitations unsuitable for transthoracic cardiac imaging.

Purpose of the Study:

• To develop and evaluate a mechanically curved RCA transducer optimized for transthoracic cardiac imaging.
• To assess the feasibility of using this transducer for advanced 3D ultrasound localization microscopy (ULM) of coronary microcirculation.

Main Methods:

• A mechanically curved RCA transducer with a toroidal surface (96x64 elements) was designed for transthoracic imaging (24x16 mm2 aperture).
• Delay and sum beamforming was implemented using analytical toroidal wave propagation, validated with Field II simulations.
• Imaging performance was assessed using a calibrated phantom, and 3D ULM was demonstrated on ex-vivo swine hearts.

Main Results:

• Experimental 3D imaging achieved depths up to 12 cm with a 30° angular aperture.
• Contrast-to-Noise ratio improved by 12 dB with an increase in virtual sources (2 to 128).
• Successful 3D ULM imaging of coronary microcirculation in a perfused ex-vivo swine heart was demonstrated.

Conclusions:

• The mechanically curved RCA transducer effectively addresses field-of-view limitations for transthoracic 3D cardiac imaging.
• This technology enables high-resolution 3D ULM, paving the way for detailed visualization of cardiac microvasculature.